The effect of extracellular matrix (laminin, fibronectin, collagen, proteoglycans) on the differentiation of embryonic corneal epithelium (avian) is being studied. We are especially interested in the effect of these molecules on the configuration of the basal epithelial surface and the organization of the basal epithelial cytoskeleton. We are using heavy meromyosin fragments (S1) to analyse the orientation of actin filaments in cells before and after exposure to matrix molecules. We are using immunohistochemistry and biochemical techniques to follow the differentiation of the epithelium. The effect of matrix molecules on fibroblast shape and migration is also being studied, using similar methods and including Nomarski optics. Avian fibroblasts from cornea, skin, heart, and limb will be compared.